The kinetics of the dyeing of a dichlorotriazinyl-reactive dye, Procion Blue MX-R, with knitted cotton fabrics have been studied using a versatile technique based on a spectrochemical channel how cell. A mechanism is derived where the simultaneous hydrolysis of the dye molecules, the physical binding of the hydrolyzed form, and the chemical fixation of the active form onto the fabric are taken into account. It is shown that the dye fixation to the fabric is controlled by a solid-liquid interfacial process that is first order with respect to the surface concentration of dye; however, the rate of this reaction is governed by the availability of sites for the adsorption of dye molecules on the fabric surface. Dyeing experiments are performed over a wide range of initial dye concentrations; supporting electrolyte concentrations and the kinetic parameters are reported. Atomic force microscopic studies indicate that mercerization pretreatment provides a disordered fiber surface which may offer additional sites for dye adsorption.